Gram-negative bacteria are ubiquitous, some of them such as Pseudomonas aeruginosa and Vibrio parahaemolyticus are pathogenic,
Enzymes capable of depolymerizing bacterial cell walls may be used to control or prevent the growth of target microorganisms such as those listed above. Lytic enzymes of this sort are much to be desired, and have long been sought, for the most part without success.
Most of the numerous bacterial cell wall degrading enzymes known to the art lyse only Gram-positive bacteria, not Gram-negative bacteria.
The surface structure of Gram-negative bacteria is exceedingly complex. An inner layer composed of peptidogliycan is enclosed by an outer layer of mostly lipopolysaccharide, lipoprotein, and lipid (C. A. Schnaitman, J. Bacteriol. 1971. 108:553 and H. D. Heilman, Eur. J. Biochem. 1972. 31:456). The multiple-track layers of the bacteria surface function as a barrier which prevents most 1lytic enzymes from reaching the underlying peptidoglycan (J. M. Ghuysen, Bacteriol. Rev. 1968. 32:425).
The inventors hereof are aware of three known in the art lytic enzymes that lyse Gram-negative bacteria (S. Murano et. al., Agric. Biol. Chem. 1974. 38:2305, T. Yoshimoto et. al., J. Ferment. Technol. 1975. 53:703 and K. Suzuki. et. al., Agric. Biol. Chem. 1985. 49:1719). These enzymes have been identified as a N-acetylglucosaminidase, N-acetytmuramidase and an endopeptidase of serine protease type, respectively.
Bacteriolytic enzymes with capability for hydrolyzing both Gram-positive and many Gram-negative bacteria, e.g., Vibrio parahaemolyticus and Salmonella arizona have not been known heretofore.